The present invention relates to roller guides used in elevators. More particularly, the present invention relates to a simplified roller guide that allows an elevator system utilizing a sliding guide system to be upgraded while maintaining required safety tolerances.
The use of both sliding and roller guides on elevators is well known in the prior art. A sliding guide is a metal plate attached to an elevator. The metal plate has a notch removed from it. The nose portion of a T-shaped guide rail protrudes into the notched out area, and the edges of the notched-out area contact and slide along the nose portion of the guide rail.
Sliding roller guides cannot generally be used on dry guide rails because of the obvious effects of unbuffered metal-on-metal contact. Heat generated by the sliding of the guide on an unlubricated guide rail causes stresses to the metal which result in the accelerated wear of the system. Rapidly worn system parts increases both the costs of operating an elevator system and the down time due to maintenance.
To avoid wear on the guide rails of a sliding guide type elevator system, a lubricant is applied to the rails. However, application of the lubricant often results in an environmentally unfriendly condition. The lubricant is either a liquid or a liquid dispersed in a soap-based carrier. Any liquid applied to a vertical surface will run, and applying either type of lubricant to a vertical surface such as an elevator guide rail will result in the lubricant running down the rail surface to the ground. Contact of the lubricant with the ground poses a threat to the environment in that the lubricant may seep into the soil and contaminate a subsurface water supply.
Furthermore, a lubricant is typically applied to the guide rails of an elevator system with an automatic mechanical oiling device. Use of a mechanical device increases the chances for mechanical breakdown. Breakdown of any piece of mechanical equipment, especially one that is not critical to the operation of a system, translates into additional labor requirements and service and maintenance costs.
Sliding guides are also a source of excessive noise during operation of the elevator. Because of the metal-on-metal contact between the sliding guide and the elevator guide rail, even with a lubricant sliding guides are generally unnecessarily noisy.
An alternative to sliding guides is conventional rolling guides. Elevator manufacturers must comply with stringent safety requirements, and these safety requirements impose strict controls on the use of conventional roller guides. Among these safety requirements is a maximum throat clearance. The throat clearance is defined as the distance between the nose of the T-shaped rail and the surface of the roller or sliding guide opposing the nose of the rail.
Prior art conventional roller guides often use three rollers. Maeda describes such a system in U.S. Pat. No. 5,632,358. In that system, one roller contacts each side of the nose portion of the T-shaped guide rail while a third roller is situated perpendicularly to the first two and contacts the edge of the nose portion of the T-shaped rail. Installing this type of conventional roller guide in place of a sliding guide in certain types of elevators will increase the throat clearance beyond the maximum allowable distance making the safeties in certain elevators either inoperable or at least out of compliance with the required safety standards.
In upgrading an elevator system using sliding guides to one using roller guides, the maximum throat clearance between the T-shaped guide rail and the elevator safety must not be exceeded. What is needed is a way to upgrade certain elevator systems that currently utilize the inefficient, environmentally unfriendly, and noisy sliding guides to an elevator system that utilizes a rolling guide system without comprising passenger safety or comfort.
The present invention is directed to an elevator car roller guide having a pair of wheels mounted on an elevator car and being configured in a coplanar fashion and positioned to rollably engage the sides of a nose portion of a T-shaped guide rail. A bumper is also mounted on the elevator car. This bumper is positioned on the elevator car to maintain proper clearance between the nose of the T-shaped guide rail and the elevator safeties, thus ensuring proper functioning of the elevator safeties. In the event that the bumper contacts the edge portion of the nose portion of the T-shaped guide rail, the bumper slidably engages the T-shaped guide rail to prevent the elevator from swaying.
The elevator car roller guide may be mounted on a base plate that can be mounted on the elevator.
The wheels of the elevator car roller guide are spring-biased toward each other to engage the sides of the nose portion of the T-shaped guide rail. Flexible plates (leaf springs) fixed at their opposing ends may be used as springs to exert the force that biases the wheels toward each other. Alternately, a plurality of flexible plates can be stacked and used to spring-bias each wheel.
The ends of each of the flexible plates may be fixed to a pair of support members. These support members may be fixed directly to the elevator car, or they may be fixed to the base plate that is fixed to the car.
The bumper may also be secured to the base plate at a point intermediate the first and the second wheel and positioned to sidably engage the nose portion of the T-shaped guide rail should contact between the bumper and the guide rail occur. The invention also contemplates a polymeric coating disposed on the bumper in order to reduce the friction generated during the contact of the bumper with the T-shaped guide rail. In the preferred embodiment, the polymeric coating would be polytetrafluoroethane (PTFE).
The axles that rotatably support the wheels may be bolted or welded or otherwise affixed to the springs. Furthermore, the axles may be mounted across the holes cut into the springs. If the spring constitutes a plurality of plates stacked upon each other, the plate situated on either end of the stack can be configured to be radially contoured around the axle.
The wheels of the present invention may be fabricated from a variety of materials. These materials include, but are not limited to, rubbers, urethanes, or any type of polytetrafluoroethane-coated material. The rubbers may be natural or synthetic, and the preferred urethane would be a polyether-based urethane. Both rubbers and urethanes provide for less noise during operation than do most other types of material. Alternately, a plurality of wheels can be mounted on a plurality of springs to engage each side of the nose portion of a T-shaped guide rail.